1. Technical Field
The present invention relate to a tablet cassette to be mounted on a tablet packing apparatus in which tablets are dispensed and packed in accordance with a prescription of a patient.
2. Description of Related Art
Conventionally, in a tablet packing apparatus, a plurality of tablet feeders are provided for every kind of tablets. Each tablet feeder comprises a tablet cassette for containing a number of tablets and a mount base on which the tablet cassette is mounted. The tablet cassette has a rotor. The outer surface of the rotor is formed with a plurality of pocket portions, each of which comprises a groove extending in an axial direction so as to hold the tablets. On the shaft of the rotor protruding downward from the bottom of the tablet cassette, a rotor gear is attached. On the bottom of the tablet cassette is attached an intermediate gear which engages with the rotor gear. In the rear portion of the bottom of tablet cassette is formed a discharge port which communicates with the pocket portions of the rotor. On the other hand, a motor is incorporated in the mount base. The shaft of the motor protrudes upward. A drive gear is fixed on the upper end of the shaft. When the tablet cassette is mounted on the mount base, the intermediate gear of the tablet cassette engages with the drive gear of the mount base. Driving the motor allows the rotor to rotate via the drive gear, the intermediate gear and the rotor gear. When the pocket portion reaches the discharge port, the tablet held in the pocket portion is discharged thorough the discharge portion and led to a packing unit though a discharge path in the mount base. When the tablet cassette is dismounted or removed from the mount base for replenishment of the tablet or inspection, the intermediate gear of the tablet cassette is disengaged from the drive gear of the mount base, thereby allowing the rotor to freely rotate. Thus, there has been a possibility that the rotor will unexpectedly rotate due to impact or vibration to cause the tablet held in the pocket of the rotor to drop from the discharge port into the packing unit, resulting in the tablet being packed in a state contaminated by other tablets.
Conventionally, there have been various suggestions for preventing the rotor from unexpectedly rotating when mounting and dismounting the tablet cassette. For example, JP 9-30501A discloses a restraint means for engaging with a gear of a rotor due to its elasticity to restrain self-rotation of the rotor when a tablet cassette is dismounted. The document also discloses a release means for releasing the engagement of the restraint means with the rotor when the tablet cassette is mounted.
The JP 9-323702A, which was filed by the same applicant as the present application, discloses an elastic engagement member that engages with a gear of a rotor to prevent the rotation of the rotor when a tablet cassette is dismounted, and an engagement release member provided on the elastic engagement member that comes into press contact with a proper position of a guide rail of a mount base to release the engagement of the elastic engagement member with the gear when the tablet cassette is mounted.
JP 10-314277A discloses an engagement means that directly engages with and disengages from a rotor so that the engagement means engages with a peripheral wall of a rotor when a tablet cassette is dismounted and disengaged from the rotor when the cassette is mounted.